Vibration recording instrument



Ap 2 93's- SJ. ZAND 2,0 8 021 VIBRATION RECORDING INSTRUMENT F iled Aug. 4, 1932 4Sheets-Sheet '1 V EN TOR.

IN STEPHEN J. ZAND.

A TTORNEY April 21, 1936. s ZAND VIBRATION RECORDING INSTRUMENT Filed Aug. 4, 1932 4 Sheets-Sheet 2 J QUE INVENTOR. arm/1m J. ZAND.

' fZi/M ATTORNEY April 21, 193 6. 4 sqJ. ZAND 2,038,021

VIBRATION RECORDING INSTRUMENT Filed Aug. 4, 1932 4 Sheets-Sheet '3 IN VEN TOR. JTEPHEN d. ZAND.

A TTORNE Y.

April '21, 1936.: s, AN 2,033,021

VIBRATION RECORDING INSTRUMENT Filed Aug. 4, 1952 4 Sheets-Sheet 4 WWII/H7 INVENTOR.

STEPHEN J ZAND.

A TT ORNE Y Patented Apr. hi, W35

UNITED STATES gran PATENT OFFICE Bendix Aviation Corporation,

South Bend,

Ind., a corporation of Delaware Application August 4, 1932, Serial No. 627,498

6 Claims.

This invention relates to recording instruments, and more particularly to means for recording vibrations.

One of the objects of the present invention is to provide novel ,means for "obtaining a record of vibrations imparted to a member from which record the form, amplitude and frequency of such vibrations may be quickly and readily ascertained.

Another object of the invention is to provide a novel instrument of the above character which is particularly adapted for recording the vibrations of a member constituting an element of a movable structure, such as an airplane.

Still another object is to provide a novel vi-= bration recording instmnnent of such size, shape and weight that the same may be readily substituted on an instrument board for another in= strument without substantially altering the vibration characteristics of said board.

A further object is to provide a novel recording device which is so constructed as to perms, nently record the amplitude along two axes, the form, and the frequency of the vibrations of a member on which the device is mounted.

A still further object is to provide a vibration recording instrument of the photographic type employing novel means. for controlling the operations of the same.

The above and further objects and novel iea tures of the invention will more fully appear from the following detailed description when taken in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not designed as a definition of the limits of the invention, reference being primarily had for this purpose to the appended claims.

In the drawings wherein like reference char actors refer to like parts throughout "the several- 55 Fig. 4 is a detail view, partly in section and with parts broken away, of one form of manual control mechanism that may be employed;

Fig. 5 is a detail view, partly in section, of the manual control mechanism taken on a slightly different line than Fig. l;

Fig. 6 is a view, partly in section, takenvon line 6-6 of Fig. 3

Fig. 7 is a partial front view showing one form of safety lock for the control mechanism;

8 is a rear view of the race of the instrument showing a preferred form of exposure indicating mechanism;

Fig. 9 is a detail view of a control knob; Figs. 10, ii. and 12 are detail views of the film and spools therefor;

Fig. 13 is a perspective view of a portion of the optical system that may be employed;

7 Fig. l i is a diagrammatic view showing the path of the light beam in the instrument ill trated;

Fig. 15 is a diagrammatic showing of a portion of the clock-work and control mechanism that is preferably employed; and

Fig. i6 is a detail view illustrating the type of vibration record which may be obtained by the use of the present invention.

Gnly one embodiment of the invention has been illustrated in the form or a vibrograph adapted to be mounted on the instrument board of aircraft or the like and, as shown (Fig. 3), the same comprises a housing 5, to the rear of which is detachahly secured by means of a. pin and slot connection (Fig. 3a) a metal cup E, the members 5, ll constituting the instrument case. Housing 5 embodies a wall 7 constituting a partition which. divides the instrument case into rear and front compartments, the latter being closed by a disc 8 secured in any suitable manner to the front end of housing The case is adapted to. be mounted on a vibrating member and, accordingly, when so mounted it is subjected to the vibrations oi said member.

Means are provided within the casing 5, 6 to project a beam of light and, since said means are mounted within the casing, the light beam will be subjected to the vibrations of the men1- her on which the casing is mounted. For this purpose, there is employed a lamp Q such as a focusing type flash light bulb connected by means of leads i (Fig. 6) and other wiring to be more fully describedvhereinafter, to a suitable source of electrical energy such as a battery (not shown). The lamp is mounted in any convenient manner in the lower portion of housing and in the front compartment substantially intermediate walls 1 I5 secured to the upper side of member i3.

As noted above, the casing 5, 5 and lamp 5 and hence the light beam illustrated by the irregular line I! (Fig. 14) are all subjected to the vibrations of the member on which said casing is mounted. A reference member having a motion which is independent of the vibration frequencies, that is, which is relatively stationary with respect to the axes along which it is desired to measure the amplitude of the vibrations, is provided in order that the movements of the light beam, and hence the amplitude, form and frequency of vibrations to which said beam is subjected, may be recorded. The reference member will be re-- ferred to as being a stationary member since it has no appreciable movement in a horizontal plane passing through the center of mass of said member, although said plane moves in unison with the vertical component of the vibrations and hence in unison with a parallel plane passing through the source of light. The reference member is constituted by a universally suspended pendulum contained within a casing whereby said pendulum remains stationary when the casing vibrates in two mutually perpendicular and horizontal directions, but no relative movement takes place between the pendulum and casing in a vertical direction. In other words, the pendulum moves in unison with the casing when the latter vibrates in a vertical direction. It is thus possible to obtain a faithful record of the horizontal vibrations in two mutually perpendicular vertical planes, and such. record can be compared with an arbitrary standard to secure the desired in formation. n

In order to provide said stationary reference member, .the'present instrument preferably is fitted with a pendulum l8 having a natural frequency such that it is substantially independent of the frequencies of vibrations imparted to the instrument case. The pendulum is mounted by means of a jeweled bearing, universal joint l9 attached in any suitable manner to the upper portion of housing 5. In order that pendulum l8 and the pendulum rod 20 may be independent of the vibration frequencies, the same should be so formed as to have a natural frequency of substantially one-fifth or less of the lowest frequency which it is desired to record. For example, if the instrument is employed on an airplane instrument board, the frequency of the pendulum should be one-fifth or less of the lowest frequency of the instrument board. It has been found that if the natural period of the pendulum is less than five times the period of the vibrations to be measured, the pendulum will not remain stationary in .a horizontal plane and the resultant record will be apparent rather than a true measure of the vibrations. I I

In order to adapt the present instrument for use in other than an upright position such as 'occurs, for example, when the same is mounted on the instrument board of an aircraft, damping means are provided for preventing excessive movement of the pendulum for maintaining the same in the path of the light beam and, this, without materially affecting the degree of freedom of relative movement of said pendulum.

able resilient material such as rubber sponge 2| into which an extension 22 of shaft lflexten'ds. Said sponge may be compressed to the desired degree in a cup-like container 23 by means of a disc 24 and a thumb screw 25, said container being secured in any suitable manner to housing 5 and having a cover 25 into which screw 25 is threaded.

Preferably, pendulum rod 20 is so mounted within housing 5 that its longitudinal axis is coaxial with aperture i5 and the light beam Il when the instrument is not being subjected to vibrations. It is also'deslrable, for the protection of the pendulum bearing It, to provide means for holding pendulum I! in a fixed position when the instrument is being transported or during violent maneuvers. Such means are provided in the form of a centralizing sleeve 21 which slidably surrounds the upper portion of sleeve l2 and is adapted to be raised to a position surrounding pendulum It by means of a bifurcated lever 25 pivotally mounted on wall I and adapted to be actuated by an ogival plunger 28 supported in housing 5 and engaging one end of said lever. Sleeve 21 is operatively associated with lever 28 by means of a pin and slot connection, and is adapted to be normally held in inoperative position by suitable resilient means such as coil spring 30.

As noted above, there is never any relative movement between the pendulum, the light beam and aperture I5 along a vertical axis passing through these members regardless of the vibrations imparted to the instrument; However, when the'instrument is subjected to vibration, lamp 9 and beam l1 each have relative movement with respect to pendulum la in two mutually perpenducular directions in a horizontal plane disposed substantially at right angles to the vertical line passing through the center of gravity of the pendulum. I

Preferably, pendulum I8 is provided on its lower surface with an angularly disposed mirror or other reflecting member for directing the vibrated beam i! into the rear compartment of the instrument case. As shown, the center portion of pendulum I8 is partially cut away and a mirror ii is mounted in the groove formed therein, said mirror being disposed at an angle of substantially 45 degrees relative to the axis of rod 20 and beam ll. Mounted in wall I of housing 5 is an objective lens 32 through which the light beam reflected from mirror 3i passes into the rear compartment of the instrument case.

' It is desirable to provide a vibration record of such size as to render the same readily readable and at the same time provide an instrument of small size. Accordingly, the present invention,

when adapted for use on airplanes, for example,

preferably includes a plurality of light reflecting members to increase the optical leverage of the vibrated beam without increasing the overall length of the instrument. To this end, there are employed a pair of stationary prisms l3 and 34 (Fig. 1) mounted, at an angle of substantially 30 degrees to the horizontal, on a plate 35 suitably attached to a rod 35 which is fixedly secured at its ends to a pair of brackets 31. The latter are attached to and extend radially inward from a partial cylinder 35 which subtends an arc of substantially 240 degrees and is secured to wall I by means of set screws, only one of which is shown. As will be noted in Fig. 14, prisms 33, 3| reflect the light beam through degrees onto a movable mirror I! to be more fully described herein- Preferably, such means are constituted by a suitafter.

Moons are provided for positioning o light= sensitive member or him in the path oi. the li beam utter it leaves mirror 39 in order t t permanent record muy. e mode from. which th amplitude, form and irc ueucy of the vihrsti under lnvestigution are readily asserts-insul this there ere providcd poi? u", or carrying casings or spools 6t and. cool-i oi. which is rotatably mounted in s, casing is sunnortcd inner end in u sui le holder mounted on c. bracket Somme: oral with the lower portion of wall l and at its outer end by moons of piste scoured to the outer end of cylinder film. led. from 3t spool over the smooth outer surface of. our oi cylinder 38, the latter provided witu on opening to which lengths dim are exposed to the light beam reflector mirror 3%. For moving the spool video. with o, central opouino; having a; the diameter thereot which is so pt rs-god by a bifurcated control sl i in. whereby spool may be slidcbly extends through E and is provided on its outer end with is control lmoh If mirror 39 and the film rclctivcly stationary. only a plurality of superimposed. exposures of the film, as shown at c, 1:, will be obtained. and it would be impossible to determine the ire quency of the vibrations from such. at record. On the other hand, it there is continuous relative movement between the two while the light beam is being reflected onto the film, a. distorted picture, such as is shown from b to c, Fig. it, will be recorded and, although the frequency would be pus. across 2 be on readily obtaincblc therefrom. the determination of the amplitude and the torm oi the vibrations would involve a tedious application of higher mathematics. The present invention comprehends the use ot a mirror and film which are relatively movable during predetermined intervals of time. Additionallm it is desirable to provide an instrument oi small weight in. order that the some may be mounted on a vibrating member without substantially altering the mass of the member and hence the vibration characteristics thereof. .11 it is desired to move the film, a. relatively large amount of power would be required,

and hence the weight of the instrument would be materially increased. Preferably, the present in-- vention includes the use of a normally stationary film, and means are provided for singularly moving the mirror so that the latter will start and stop at predetermined intervals of time during,' each revolution. To this end, the instrument iucludes a. skeleton clockwork or spring motor 48 comprising. a. main spring casing and gear 49 (Fig. 15), a. step-up gear train including gears- 50 to 54 inclusive, a. driven gear 55 and a gear to the shait of which mirror 35 is secured. In order that mirror 3 may be started and stopped at predetermined intervals during each revolu. tion, gear 55 has separated sectors on which no teeth are out. Thus, when a; smooth sector of gear 55 is adjacent gear 56, the latter and hence mirror 39, will be stationmn- The relative sizes of gears 55 and 58 and the number of teeth thereon are proportioned so that an equal number of revolutions will be made by each. 5

It will be noted that the driving means provided is not a. true clockwork since no escapemcnt wheel is employed and thalt. therefore, the intervals of movement of mirror 39 must be determined by comparison with a. standard watch and, in order that these intervals may be maintained tl'irough idler gecr constant, means are provided for winding the by s. gecr ill (Figs. and 5) secured to shaft :56, being adapted to wind the main spring idly turning knob G'i, then. through equal singular distances, in o. monuerfco be set Ecrth hereafter, for each exposure, 2min spring will thereby be wound to on equal tension for each orzuosure.

Novel means are provided for releasing the shove clockwork: after the main spring has been wound stopping the some after each revolution of 35). As shown, sucl'i means comprise clever 2 and plvoted intermediate its ends and. providcd with c lug 66 which is adapted fit c mating recess GI formed in s. projecting hub portion of "gear 55. Suitable resi t means, such as coil spring 62. provided r normally holding lug so into recess thereby preventing the o motion of the clockwork. When is wlthdrowu from the recess, the clockwork will be released for rotsting mirror as described above. After one revolt on of the driving gear 55, lug so will again engage recess end stop the clockwork. This method oi abruptly stopping the mechanism would soon prove detn'mentsl to the bearings of gear 55. so means are, therefore, provided in the form of a friction brakelor gradually bringing the clockwork. mechanism. rest. In the form illustrated, o. broke shoe tSls adopted to engage s. friction surface on gear wheel 54? (Figs. 2 and 15) just prior to the instant that lug Gill seats itseli in recess 66. Brake shoe 83 is pivotaliy mounted on is suitable pin and is operatively connected to a lever arm 6, the latter being adapted to be actuated against the resilient effort of a. spring 65 by a. pin projecting laterally from lever 58 for releasing said brake.

In order to insure that bulb 3 will always be lighted when an exposure is being made, means are provided whereby the some will be lighted and extinguished simultaneously with the starting and stopping of the clockwork described above. The supply lines ill are connected to the instrument by means of a, plug 6%, one terminal of which is grounded through. casing 5 to one terminal of bulb 9 (Fig. 6). The other terminal of said bulb is connected to the source of power through lead 51 (Fig. 1) normally open switch. 68 (Fig. 2) and lead 6% to a socket ill (Fig. 6) into which plug. 66 is adapted to be inserted. Switch 68 is normally held in open. position by means of a. spring H and is adapted to be closed against the efforts of said spring by lever to when the latter is actuated for releasing the clockwork.

A small bulb 12 (Fig. ll may be included in the above circuit 501' indicating when the instrument is in operation.

Means for indicating the number of exposures made on the roll of films in use are provided and,

as shown, such means comprise a dial N (Fig. 8) in the form of s. ratchet wheel mounted on the inner face of plate (land provided with 's. knob 14 (Fig. 7) for turning the some directly. Dial 73 has a series of numbers engraved thereon, one of which is visible through an opening l5 in pinto 8 for indicating the number of exposures mode. A spring-pressed pawl 16 is provided for prcvcnting the rotation of said dial in but one direction.

The parts of the instrument thus for described are so proportioned that a. new length of film is exposed through window 55, and the main spring of the clockwork is wound to the desired tension tuating lever 88 to release the clockwork and for moving dial 18 one notch for each 180 degrees of rotation of shaft 48. The illustrated means for these purposes comprise a cam 11 having two diametrically opposed lobes (Figs. 4 and 6) mounted on said shaft for rotation therewith. For actuating lever 58, one of the lobes of cam 11 engages a crank pin 18 connected to a sleeve 18 which is in turn secured to a rod 88. The latter is rotatably supported by a hub formed in wall I and projects rearwardly into the rear compartment of easing 8, 8 where it is provided with a radially projecting cam-shaped pin 8| (Fig. 2) which is adapted to engage and actuate lever 88 upon the angular movement of said rod. Similar means, including a lever 82 (Fig. 8), having a spring-pressed pawl 83 pivotally mounted on the upper end thereof for engaging dial I8, are em-'- ployed for rotating said dial. Lever 82 is provided at its lower end with a laterally projecting pin84, which latter is adapted to be engaged by the lobes of cam Tl, the pivot point of said lever being such that dial l3 is'moved one notch for each one-half revolution of knob 81. Lever 82 is held in normal position against a stop 88 ,cesses 88 (Figs. 7 and 9) spaced 180 degrees apart in the inner periphery of the same into which pin 88 is adapted to fit for locking said knob in position. A suitable spring 8| is provided foryieldingly holding pin 88 in engagement with the inner periphery of knob 81.

When all of the light sensitive film has been exposed, it is necessary to wind the additional tape, provided on spool 8|, onto the spool 48 so that the film will not be exposed to light when the same is removed for development, and it is desirable, of course, to do this without setting the instrument into operation. To this end, shaft 88 is mounted for movement in the direction of its longitudinal axis (Fig. 5) so that when the same is moved to its outer'position, gear 81' will be out of mesh with gear 88, cam 11 will be free to rotate without engaging crank pin 18, .and knob 81 will be clear of pin 88, while the bifurcations on the end of said shaft will remain in engagement with the usual pin in spool 48 for rotating the same. Shaft 88 may be providedwith a pair of suitably spaced annular grooves 880 into which the end of a spring-pressed pin 82 is adapted to fit, thereby holding said shaft in the desired positions under normal operating conditions.

When it is desired to make a record of the vibrations being imparted to the instrument, it is only necessary for the operative to move arm 81 temporarily to the left as seen in Fig. 1 and turn wheel 88.

through gears 81, 88, cam 17 engages pin 88 for moving dial 18 one notch, and said cam also engages crank thereby rotating rod 88 and actuating lever 88 by means of pin 8|, whereby the circuit to lights 8 and I2 is closed through switch 88, lug 88 is withdrawn from recess 8| and brake shoe 88 is moved out of engagement with The clockwork is then free to rotate mirror 88 while the vibrating beam II is being reflected thereon. The mirror will be alternately stopped and rotated as the separated sectors of teeth on driving gear 88 engage gear 88. When mirror 88 is stopped, a number of superimposed exposures are recorded such as at a (Fig. 18), from which record the amplitude along two axes and the form of the vibrations are readily ascertained. While there is relative movement between mirror 88 and the film, a record such as fom b to "c is obtained. Since the interval between stops is of predetermined length, as pointed out above, the frequency of the-vibrations may be determined by knowing the number of vibrations between stops. When gear 88 has made one complete revolution, and at the instant lug 88 starts to seat itself in recess 8 l, brake shoe 88 will engage wheel 88, therby slowing down the clockwork mechanism. As lug 88 seats itself into recess 8|, switch 88 is opened and the instrument is restored to its normal inoperative state.

Before the instrument is placed in use, it should be properly calibrated by determining the ampliilcation constants for the two axes along which the amplitudes are measured. Any vibrating member which follows a simple harmonic motion of known amplitude, and to which the instrument can be conveniently attached, may be used as a standard. The constants may be readily ob-- tained from a series of records taken with the instrument so mounted. I

There is thus provided a vibrograph adapted to visually record vibrations. From the record on the film, the frequency and the amplitude, in two planes, of the vibrations may bereadily obtained. The instrument is of very small size and weight and will not change the vibration characteristics of the member, such as an instrument panelpon which it is mounted. Various changes may be made in the details of construction as, for example, in the clockwork gearing, as will be appreciated by those skilled in the art. Reference will accordingly be had to the appended claims for a definition of the limits of the invention.

What is claimed is: I r

1. In a vibration recording instrument of the type having a casing, means in said casing for projecting a beam of light, a relatively stationary reference member in said casing, means on said.

ror, common means for moving the film to provide an unexposed portion thereof in the path of the beam, for simultaneously winding said spring motor, and for releasing said motor to operate the mirror after the. film has been moved, and means for automatically stopping said motor after the mirror has made one revolution.

2. In a vibration recording instrument of the type having a casing adapted to be mounted on and subjected to the vibrations of a member, means in said casing for projecting a beam of light. a reference member universally mounted bination of a spring motor for rotating said mirin said casing and having such mass that it remains stationary when the casing is subjected to vibrations in two mutually perpendicular horizontal directions, means on said reference member for reflecting said beam, a light sensitive fllm which is relatively stationary during recording, and a rotatable mirror for reflecting said beam onto and along said fllm, the combination of a motor mechanism for rotating said mirror, means for automatically stopping said motor after said mirror has made one complete revolution, and means for stopping said mirror at predetermined intervals of time during each revolution while said motor is running whereby a single continuous trace is produced on the film showing the amplitude and frequency of vibrations in two planes.

3. In a vibration recording instrument according to claim 2, means effective upon operation of the film moving means for simultaneously winding the motor mechanism, releasing said motor mechanism to operate the mirror after it has been wound and a new sectionpf fllm exposed, and for energizing the light projecting means.

4. In a vibration recording instrument according to claim '2, means effective upon operation of the film moving means for simultaneously winding the motor mechanism, releasing said motor mechanism to operate the mirror after it has been wound and a new section of film exposed, and for energizing the light projecting means, and means for automatically stopping said motor mechanism and for simultaneously deenergizing said light projecting means after the mirror has made a complete revolution.

lum for reflecting said beam, means for increas-' ing the optical leverage of said light beam, a rotatable mirror for reflecting said beam, a spring motor including a driving gear having separated sectors of teeth thereon for intermittently actuating said mirror, and a light sensitive film in the path of the beam reflected from the mirror.

6. In a vibration recording instrument, a casing, means in said casing for projecting a light beam, a reference member universally mounted in said casing and having such mass that it remains stationary when the casing is subjected to vibrations in two mutually perependicular horizontal directions, means including a light directing member on said reference member interposed in the path of said beam, a light sensitive film, a rotatable reflector for directing said beam onto said fllm, a spring motor for imparting intermittent, angular movement to said reflector, a lever pivoted intermediate its ends, means on said lever for stopping said motor after each revolution of said mirror, switch means for said light projecting means adapted to be actuated by said lever, and common means for actuating said lever and for energizing said motor.

STEPHEN J. ZAND. 

